Maybe ,just maybe, its not an age barrier but a face barrier ?
Oh you are back.
Anyway it's true, some people have age-related préjugés. My brother (he is 30) is so damn insufferable. "I really can't understand how you can be friends with someone who is 10 years older than you, really at work, I notice these people who are your age, Deborah, and they are so immature, we really don't belong to the same world. They care about getting drunk, I have much more serious worries, I have two kids now."
He is also the most stubborn dude I've ever known so whatever...
So I guess... as long as you do your work, are always OK to make your job, and all nice to others, like a smiley then chit chat then a cup of coffee during your short break with your workmates... Should be good enough...
But yes, if you want to get a bold position or something, it will likely be hampered by age.
Maybe try to not show too much your young age by talking about getting drunk, etc etc ?
But to be honest, my brother overuses the age excuse when I am trying to debate/have a serious discussion with him or even when he is tired so doesn't want to talk to me.
It's quite common, I already felt that when I worked in a factory.
Main thing : focus on your job, show you are enthusiastic and ready to learn more from them...